Field
The present disclosure relates to network management. More specifically, the present disclosure relates to a method and system for efficient multicast topology construction in a routed network.
Related Art
The exponential growth of the Internet has made it a popular delivery medium for multimedia applications, such as video on demand and television. Such applications have brought with them an increasing demand for bandwidth. As a result, equipment vendors race to build larger and faster switches with versatile capabilities, such as multicasting, to move more traffic efficiently. However, the size of a switch cannot grow infinitely. It is limited by physical space, power consumption, and design complexity, to name a few factors. Furthermore, switches with higher capability are usually more complex and expensive. More importantly, because an overly large and complex system often does not provide economy of scale, simply increasing the size and capability of a switch may prove economically unviable due to the increased per-port cost.
One way to meet this challenge is to interconnect a number of switches and routers to support a large number of multicast users. Interconnecting such a large number of switches in a layer-2 network is often not scalable. This issue can be solved by interconnecting switches via layer-3 and creating a routed network. Deploying a routed network requires configurations, such as assigning an address for a respective interface and configuring routing protocols for the switch. As layer-3 (e.g., Internet Protocol or IP) routing technologies continue to evolve, more flexible functionalities, such as a distributed virtualized layer-2 network across layer-3 networks, are being supported.
An efficient multicast topology is usually desirable in a network. A network administrator uses a multicast topology to manage the distribution of data traffic belonging to a corresponding multicast group in the network. A multicast topology in a layer-3 network can span multiple virtual local area networks (VLANs) and layer-3 sub networks (subnets). A routed network typically carries data traffic belonging to multiple multicast groups. A respective multicast group can have a different instance of a multicast topology within the same routed network.
For a specific multicast group, a multicast topology usually corresponds to a multicast distribution tree (can also be referred to as a multicast tree), which provides an active data path between a respective router in the routed network and a root router of the multicast group. The root router is coupled to a source associated with the corresponding multicast group. With existing technologies, obtaining such a data path in a routed network requires device-specific information (e.g., an IP address) of at least one router (usually the terminating router or leaf router) in a path from the root router (e.g., one branch of the corresponding multicast tree). As a result, only one such data path for one multicast group can be obtained at a time. Consequently, constructing a multicast topology for a multicast group can be tedious and repetitious.
While multicast brings many desirable features to a network, some issues remain unsolved in efficient multicast topology construction in a routed network.